Add Threat Insights maintainers to CODEOWNERS

.gitlab/CODEOWNERS

@@ -69,6 +69,18 @@ Dangerfile @gl-quality/eng-prod
 /ee/app/models/project_alias.rb @patrickbajao
 /ee/lib/api/project_aliases.rb @patrickbajao
 
+# Secure & Defend ownership delineation
+# https://gitlab.com/gitlab-com/www-gitlab-com/-/merge_requests/55713#note_380129762
+/ee/app/models/vulnerability.rb @gitlab-org/secure/threat-insights-backend-team
+/ee/app/models/security/ @gitlab-org/secure/threat-insights-backend-team
+/ee/app/models/vulnerabilities/ @gitlab-org/secure/threat-insights-backend-team
+/ee/lib/gitlab/ci/parsers/license_compliance/ @gitlab-org/secure/composition-analysis-be
+/ee/lib/gitlab/ci/parsers/security/ @gitlab-org/secure/composition-analysis-be @gitlab-org/secure/dynamic-analysis-be @gitlab-org/secure/static-analysis-be @gitlab-org/secure/fuzzing-be
+/ee/lib/gitlab/ci/reports/coverage_fuzzing/ @gitlab-org/secure/fuzzing-be
+/ee/lib/gitlab/ci/reports/dependency_list/ @gitlab-org/secure/composition-analysis-be
+/ee/lib/gitlab/ci/reports/license_scanning/ @gitlab-org/secure/composition-analysis-be
+/ee/lib/gitlab/ci/reports/security/ @gitlab-org/secure/composition-analysis-be @gitlab-org/secure/dynamic-analysis-be @gitlab-org/secure/static-analysis-be @gitlab-org/secure/fuzzing-be
+
 [Code Owners]
 /ee/lib/gitlab/code_owners.rb @reprazent @kerrizor @garyh
 /ee/lib/gitlab/code_owners/ @reprazent @kerrizor @garyh